Role of Slow Waves in the Progression of Neurodegeneration in Isolated REM Sleep Behavior Disorder

This study is investigating whether stimulating slow brain waves during sleep — using gentle sounds played through headphones — can slow the progression of neurodegeneration in people with a condition called isolated REM sleep behavior disorder (iRBD), where people physically act out their dreams. This condition often precedes Parkinson's disease, and researchers want to see if this sleep-based treatment can delay or prevent that transition. **You may be eligible if:** - You have been diagnosed with isolated REM sleep behavior disorder confirmed by a sleep study - You also have either reduced sense of smell and movement abnormalities, OR a recent Parkinson's diagnosis (within 2 years) - You are not currently on dopamine-based Parkinson's medication and don't expect to start during the study - You can hear the audio tones used in the treatment - You are able to apply the intervention at home, with or without a housemate's help - You speak German, French, or Italian **You may NOT be eligible if:** - You have significant sleep apnea (AHI > 15 per hour) unless treated with CPAP - You have restless legs syndrome, dementia, or severe depression - You have atypical Parkinson's syndrome - You are pregnant or planning to become pregnant - You regularly use sedatives, benzodiazepines, or have a substance use disorder - You have a hearing impairment that prevents you from hearing the tones Talk to your doctor to see if this trial is right for you.